1. Field of the Invention
The present invention relates to a method of automatically setting photographing conditions of a photography apparatus for photographing a person, and a photography apparatus using the method.
2. Description of the Related Art
In photography apparatuses such as digital cameras, automatic adjustment of focus and diaphragm has conventionally been carried out. Further, in recent years, photography apparatuses have been proposed, which detect a human face in a preview image acquired before photographing, and automatically adjust the focus to the detected face (eyes) (see, for example, Japanese Unexamined Patent Publication No. 2005-128156). In the invention disclosed in Japanese Unexamined Patent Publication No. 2005-128156, human eyes are detected from image data acquired through photographing by an image taking unit, and information representing the position and the size of the detected eyes are obtained. Then, a focus frame is set based on the detected human eyes and the position and the size thereof. Thereafter, the focusing lens is controlled so that the face within the set focus frame is focused.
The above-described face detection uses luminance information and edge information of images. In this face detection process, if luminance information and/or edge information of a face area in an image do not represent characteristic structures of a face, the face cannot be detected. When a person is photographed using, for example, a digital camera, the face of the person can be detected from an acquired image if photographing conditions, such as focus and exposure, are suitable for photographing the person. However, if the photographing conditions are not suitable for photographing the person, the face within the image may not have characteristic structures that make the face discriminable as the face, and therefore, the face may not be detected automatically.
Therefore, in the invention disclosed in Japanese Unexamined Patent Publication No. 2005-128156, if an image used for the first face detection is acquired with the focal position and/or exposure condition not being optimal, the face in the image may not have edge information and/or luminance information that are characteristic to a face. This makes it difficult to detect the face in the image and to set the focal position using the detected face, and sometimes a face of a person may not be correctly focused when photographing the person.